The present invention relates generally to a method of normalizing clinical laboratory measurements. In particular, the present invention relates to a method of normalizing clinical laboratory measurements across a range of measurement devices and methods.
Medical practitioners including physicians utilize clinical laboratory measurements in making treatment decisions and diagnostic determinations for patients. These measurements are generally made using a variety of techniques that may directly measure the amount of a target compound in blood or urine, or they may indirectly measure the amount of a target compound by using a reagent to produce a secondary compound that can be measured more easily and/or accurately than the target compound. The target compounds may be electrolytes, enzymes, antibodies, or other compounds of clinical interest.
Currently, clinical laboratory measurements are compared to a reference range. The reference range provides a range of values for a particular measurement that is considered normal and is defined by a maximum value and a minimum value. The reference range for a particular measurement may vary from one clinical laboratory to another depending on the testing equipment used, the lot number of any reagents used, and the date on which the measurement is taken. Each time a new reagent lot number is used, a new reference range must be determined for the method and testing instrument being used by employing reference samples for calibration.
As a result, the measured value of a target compound provided by a particular testing method is not useful as an absolute measurement, but only as the measured value compares to a specific reference range that will vary depending on the lot number of reagent used. In addition, the reference range for “normal” valued may vary for patients of different demographic groups. For example, a physician may recommend medical intervention for a patient who is 60 years old with a particular measured cholesterol level and forgo medical intervention for a 20 year old patient with the same measured cholesterol level. This shows that the reference ranges for some measured values are only useful for particular age groups.
The fact that the measured values and reference ranges may vary from laboratory to laboratory and from patient to patient results in a complicated evaluation for physicians and other medical practitioners when it comes to evaluating medical decision points. Such complexity not only consumes resources, but makes the sharing of information between facilities difficult and increases the chance of medical errors.
Accordingly, there is a need for a method of normalizing clinical laboratory measurements that simplifies the process of comparing a level of a target compound to a reference range.